![Alexei Starovoitov](/assets/img/avatar_default.png)
Move three global variables protected by bpf_verifier_lock into 'struct bpf_verifier_env' to allow parallel verification. Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
349 lines
12 KiB
C
349 lines
12 KiB
C
/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of version 2 of the GNU General Public
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* License as published by the Free Software Foundation.
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*/
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#ifndef _LINUX_BPF_VERIFIER_H
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#define _LINUX_BPF_VERIFIER_H 1
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#include <linux/bpf.h> /* for enum bpf_reg_type */
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#include <linux/filter.h> /* for MAX_BPF_STACK */
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#include <linux/tnum.h>
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/* Maximum variable offset umax_value permitted when resolving memory accesses.
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* In practice this is far bigger than any realistic pointer offset; this limit
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* ensures that umax_value + (int)off + (int)size cannot overflow a u64.
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*/
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#define BPF_MAX_VAR_OFF (1 << 29)
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/* Maximum variable size permitted for ARG_CONST_SIZE[_OR_ZERO]. This ensures
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* that converting umax_value to int cannot overflow.
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*/
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#define BPF_MAX_VAR_SIZ (1 << 29)
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/* Liveness marks, used for registers and spilled-regs (in stack slots).
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* Read marks propagate upwards until they find a write mark; they record that
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* "one of this state's descendants read this reg" (and therefore the reg is
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* relevant for states_equal() checks).
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* Write marks collect downwards and do not propagate; they record that "the
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* straight-line code that reached this state (from its parent) wrote this reg"
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* (and therefore that reads propagated from this state or its descendants
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* should not propagate to its parent).
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* A state with a write mark can receive read marks; it just won't propagate
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* them to its parent, since the write mark is a property, not of the state,
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* but of the link between it and its parent. See mark_reg_read() and
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* mark_stack_slot_read() in kernel/bpf/verifier.c.
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*/
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enum bpf_reg_liveness {
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REG_LIVE_NONE = 0, /* reg hasn't been read or written this branch */
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REG_LIVE_READ, /* reg was read, so we're sensitive to initial value */
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REG_LIVE_WRITTEN, /* reg was written first, screening off later reads */
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REG_LIVE_DONE = 4, /* liveness won't be updating this register anymore */
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};
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struct bpf_reg_state {
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/* Ordering of fields matters. See states_equal() */
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enum bpf_reg_type type;
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union {
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/* valid when type == PTR_TO_PACKET */
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u16 range;
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/* valid when type == CONST_PTR_TO_MAP | PTR_TO_MAP_VALUE |
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* PTR_TO_MAP_VALUE_OR_NULL
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*/
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struct bpf_map *map_ptr;
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/* Max size from any of the above. */
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unsigned long raw;
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};
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/* Fixed part of pointer offset, pointer types only */
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s32 off;
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/* For PTR_TO_PACKET, used to find other pointers with the same variable
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* offset, so they can share range knowledge.
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* For PTR_TO_MAP_VALUE_OR_NULL this is used to share which map value we
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* came from, when one is tested for != NULL.
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* For PTR_TO_SOCKET this is used to share which pointers retain the
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* same reference to the socket, to determine proper reference freeing.
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*/
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u32 id;
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/* PTR_TO_SOCKET and PTR_TO_TCP_SOCK could be a ptr returned
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* from a pointer-cast helper, bpf_sk_fullsock() and
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* bpf_tcp_sock().
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*
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* Consider the following where "sk" is a reference counted
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* pointer returned from "sk = bpf_sk_lookup_tcp();":
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*
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* 1: sk = bpf_sk_lookup_tcp();
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* 2: if (!sk) { return 0; }
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* 3: fullsock = bpf_sk_fullsock(sk);
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* 4: if (!fullsock) { bpf_sk_release(sk); return 0; }
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* 5: tp = bpf_tcp_sock(fullsock);
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* 6: if (!tp) { bpf_sk_release(sk); return 0; }
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* 7: bpf_sk_release(sk);
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* 8: snd_cwnd = tp->snd_cwnd; // verifier will complain
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*
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* After bpf_sk_release(sk) at line 7, both "fullsock" ptr and
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* "tp" ptr should be invalidated also. In order to do that,
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* the reg holding "fullsock" and "sk" need to remember
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* the original refcounted ptr id (i.e. sk_reg->id) in ref_obj_id
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* such that the verifier can reset all regs which have
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* ref_obj_id matching the sk_reg->id.
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*
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* sk_reg->ref_obj_id is set to sk_reg->id at line 1.
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* sk_reg->id will stay as NULL-marking purpose only.
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* After NULL-marking is done, sk_reg->id can be reset to 0.
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*
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* After "fullsock = bpf_sk_fullsock(sk);" at line 3,
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* fullsock_reg->ref_obj_id is set to sk_reg->ref_obj_id.
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*
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* After "tp = bpf_tcp_sock(fullsock);" at line 5,
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* tp_reg->ref_obj_id is set to fullsock_reg->ref_obj_id
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* which is the same as sk_reg->ref_obj_id.
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*
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* From the verifier perspective, if sk, fullsock and tp
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* are not NULL, they are the same ptr with different
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* reg->type. In particular, bpf_sk_release(tp) is also
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* allowed and has the same effect as bpf_sk_release(sk).
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*/
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u32 ref_obj_id;
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/* For scalar types (SCALAR_VALUE), this represents our knowledge of
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* the actual value.
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* For pointer types, this represents the variable part of the offset
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* from the pointed-to object, and is shared with all bpf_reg_states
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* with the same id as us.
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*/
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struct tnum var_off;
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/* Used to determine if any memory access using this register will
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* result in a bad access.
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* These refer to the same value as var_off, not necessarily the actual
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* contents of the register.
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*/
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s64 smin_value; /* minimum possible (s64)value */
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s64 smax_value; /* maximum possible (s64)value */
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u64 umin_value; /* minimum possible (u64)value */
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u64 umax_value; /* maximum possible (u64)value */
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/* parentage chain for liveness checking */
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struct bpf_reg_state *parent;
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/* Inside the callee two registers can be both PTR_TO_STACK like
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* R1=fp-8 and R2=fp-8, but one of them points to this function stack
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* while another to the caller's stack. To differentiate them 'frameno'
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* is used which is an index in bpf_verifier_state->frame[] array
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* pointing to bpf_func_state.
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*/
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u32 frameno;
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enum bpf_reg_liveness live;
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};
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enum bpf_stack_slot_type {
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STACK_INVALID, /* nothing was stored in this stack slot */
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STACK_SPILL, /* register spilled into stack */
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STACK_MISC, /* BPF program wrote some data into this slot */
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STACK_ZERO, /* BPF program wrote constant zero */
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};
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#define BPF_REG_SIZE 8 /* size of eBPF register in bytes */
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struct bpf_stack_state {
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struct bpf_reg_state spilled_ptr;
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u8 slot_type[BPF_REG_SIZE];
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};
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struct bpf_reference_state {
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/* Track each reference created with a unique id, even if the same
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* instruction creates the reference multiple times (eg, via CALL).
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*/
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int id;
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/* Instruction where the allocation of this reference occurred. This
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* is used purely to inform the user of a reference leak.
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*/
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int insn_idx;
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};
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/* state of the program:
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* type of all registers and stack info
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*/
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struct bpf_func_state {
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struct bpf_reg_state regs[MAX_BPF_REG];
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/* index of call instruction that called into this func */
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int callsite;
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/* stack frame number of this function state from pov of
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* enclosing bpf_verifier_state.
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* 0 = main function, 1 = first callee.
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*/
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u32 frameno;
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/* subprog number == index within subprog_stack_depth
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* zero == main subprog
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*/
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u32 subprogno;
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/* The following fields should be last. See copy_func_state() */
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int acquired_refs;
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struct bpf_reference_state *refs;
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int allocated_stack;
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struct bpf_stack_state *stack;
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};
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#define MAX_CALL_FRAMES 8
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struct bpf_verifier_state {
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/* call stack tracking */
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struct bpf_func_state *frame[MAX_CALL_FRAMES];
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u32 curframe;
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u32 active_spin_lock;
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bool speculative;
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};
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#define bpf_get_spilled_reg(slot, frame) \
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(((slot < frame->allocated_stack / BPF_REG_SIZE) && \
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(frame->stack[slot].slot_type[0] == STACK_SPILL)) \
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? &frame->stack[slot].spilled_ptr : NULL)
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/* Iterate over 'frame', setting 'reg' to either NULL or a spilled register. */
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#define bpf_for_each_spilled_reg(iter, frame, reg) \
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for (iter = 0, reg = bpf_get_spilled_reg(iter, frame); \
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iter < frame->allocated_stack / BPF_REG_SIZE; \
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iter++, reg = bpf_get_spilled_reg(iter, frame))
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/* linked list of verifier states used to prune search */
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struct bpf_verifier_state_list {
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struct bpf_verifier_state state;
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struct bpf_verifier_state_list *next;
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int miss_cnt, hit_cnt;
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};
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/* Possible states for alu_state member. */
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#define BPF_ALU_SANITIZE_SRC 1U
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#define BPF_ALU_SANITIZE_DST 2U
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#define BPF_ALU_NEG_VALUE (1U << 2)
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#define BPF_ALU_NON_POINTER (1U << 3)
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#define BPF_ALU_SANITIZE (BPF_ALU_SANITIZE_SRC | \
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BPF_ALU_SANITIZE_DST)
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struct bpf_insn_aux_data {
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union {
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enum bpf_reg_type ptr_type; /* pointer type for load/store insns */
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unsigned long map_state; /* pointer/poison value for maps */
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s32 call_imm; /* saved imm field of call insn */
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u32 alu_limit; /* limit for add/sub register with pointer */
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struct {
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u32 map_index; /* index into used_maps[] */
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u32 map_off; /* offset from value base address */
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};
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};
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int ctx_field_size; /* the ctx field size for load insn, maybe 0 */
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int sanitize_stack_off; /* stack slot to be cleared */
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bool seen; /* this insn was processed by the verifier */
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u8 alu_state; /* used in combination with alu_limit */
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unsigned int orig_idx; /* original instruction index */
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};
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#define MAX_USED_MAPS 64 /* max number of maps accessed by one eBPF program */
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#define BPF_VERIFIER_TMP_LOG_SIZE 1024
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struct bpf_verifier_log {
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u32 level;
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char kbuf[BPF_VERIFIER_TMP_LOG_SIZE];
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char __user *ubuf;
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u32 len_used;
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u32 len_total;
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};
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static inline bool bpf_verifier_log_full(const struct bpf_verifier_log *log)
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{
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return log->len_used >= log->len_total - 1;
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}
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#define BPF_LOG_LEVEL1 1
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#define BPF_LOG_LEVEL2 2
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#define BPF_LOG_STATS 4
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#define BPF_LOG_LEVEL (BPF_LOG_LEVEL1 | BPF_LOG_LEVEL2)
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#define BPF_LOG_MASK (BPF_LOG_LEVEL | BPF_LOG_STATS)
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static inline bool bpf_verifier_log_needed(const struct bpf_verifier_log *log)
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{
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return log->level && log->ubuf && !bpf_verifier_log_full(log);
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}
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#define BPF_MAX_SUBPROGS 256
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struct bpf_subprog_info {
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u32 start; /* insn idx of function entry point */
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u32 linfo_idx; /* The idx to the main_prog->aux->linfo */
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u16 stack_depth; /* max. stack depth used by this function */
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};
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/* single container for all structs
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* one verifier_env per bpf_check() call
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*/
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struct bpf_verifier_env {
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u32 insn_idx;
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u32 prev_insn_idx;
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struct bpf_prog *prog; /* eBPF program being verified */
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const struct bpf_verifier_ops *ops;
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struct bpf_verifier_stack_elem *head; /* stack of verifier states to be processed */
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int stack_size; /* number of states to be processed */
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bool strict_alignment; /* perform strict pointer alignment checks */
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struct bpf_verifier_state *cur_state; /* current verifier state */
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struct bpf_verifier_state_list **explored_states; /* search pruning optimization */
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struct bpf_verifier_state_list *free_list;
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struct bpf_map *used_maps[MAX_USED_MAPS]; /* array of map's used by eBPF program */
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u32 used_map_cnt; /* number of used maps */
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u32 id_gen; /* used to generate unique reg IDs */
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bool allow_ptr_leaks;
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bool seen_direct_write;
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struct bpf_insn_aux_data *insn_aux_data; /* array of per-insn state */
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const struct bpf_line_info *prev_linfo;
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struct bpf_verifier_log log;
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struct bpf_subprog_info subprog_info[BPF_MAX_SUBPROGS + 1];
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struct {
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int *insn_state;
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int *insn_stack;
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int cur_stack;
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} cfg;
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u32 subprog_cnt;
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/* number of instructions analyzed by the verifier */
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u32 insn_processed;
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/* total verification time */
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u64 verification_time;
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/* maximum number of verifier states kept in 'branching' instructions */
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u32 max_states_per_insn;
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/* total number of allocated verifier states */
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u32 total_states;
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/* some states are freed during program analysis.
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* this is peak number of states. this number dominates kernel
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* memory consumption during verification
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*/
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u32 peak_states;
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/* longest register parentage chain walked for liveness marking */
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u32 longest_mark_read_walk;
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};
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__printf(2, 0) void bpf_verifier_vlog(struct bpf_verifier_log *log,
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const char *fmt, va_list args);
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__printf(2, 3) void bpf_verifier_log_write(struct bpf_verifier_env *env,
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const char *fmt, ...);
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static inline struct bpf_func_state *cur_func(struct bpf_verifier_env *env)
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{
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struct bpf_verifier_state *cur = env->cur_state;
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return cur->frame[cur->curframe];
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}
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static inline struct bpf_reg_state *cur_regs(struct bpf_verifier_env *env)
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{
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return cur_func(env)->regs;
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}
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int bpf_prog_offload_verifier_prep(struct bpf_prog *prog);
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int bpf_prog_offload_verify_insn(struct bpf_verifier_env *env,
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int insn_idx, int prev_insn_idx);
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int bpf_prog_offload_finalize(struct bpf_verifier_env *env);
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void
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bpf_prog_offload_replace_insn(struct bpf_verifier_env *env, u32 off,
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struct bpf_insn *insn);
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void
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bpf_prog_offload_remove_insns(struct bpf_verifier_env *env, u32 off, u32 cnt);
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#endif /* _LINUX_BPF_VERIFIER_H */
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